[joosters]

I think the duplicate detector looks at exact URL matches. Things like a trailing / or ? will let a new story go through.

[ot]

The duplicate detector is usually quite more clever than just exact URL match. Why the downvote?

EDIT: In fact, I just tried to re-submit an existing link by adding a question mark and it didn't go through.

[peteretep]

    > The duplicate detector is usually quite more clever than 
    > just exact URL match

This doesn't match my experience, but then I usually editorialize my titles if I'm resubmitting something I know is here already.